The present invention relates generally to agricultural implements and, more particularly, to a detachable hub and sprocket for use with the mechanical drive transmission of an agricultural implement.
Some agricultural implements, such as planters and seeders, have various systems or devices that are powered by power that is derived from rotation of a ground engaging wheel of the implement. For example, a planter will typically deposit seed as a function of the rotational speed of the ground engaging wheel. However, most planters will also include a mechanical drive system or transmission to provide some control in the seed deposition rate as a function of the rotational speed of the ground engaging wheel. In other words, the mechanical drive system will include an output shaft that interfaces with the seed metering or seed deposition system and a set of gears will be used to control the rotational speed of the output shaft relative to the speed of the ground engaging wheel.
In a typical arrangement, a chain or belt drive is used to rotate a driven shaft with rotation of the axle (drive shaft) of the ground engaging wheel. A sprocket (also referred to as a cog or gear ring) is mounted to each end of the driven shaft and the sprockets will typically have different diameters (gear ratios) so that the output shaft, which is connected to one of the sprockets by a chain drive, will rotate at a different rotational speed than the drive shaft. As known in the art, the gear ratios of the sprockets will dictate the relative differences in the rotational speed of the output shaft and the drive shaft. And, since the rotational speed of the output shaft dictates the rate by which seed or other particulate matter is deposited onto the planting surface, the gear ratios will also dictate the seed deposition rate.
Different types of seed and field conditions will often require different seed deposition rates. Therefore, a planter will often require a large number of gear ratios to achieve a large range of desired seed populations to accommodate variations in seed types and field conditions. Typically, a change in the drive ratio of the mechanical drive system is accomplished by swapping sprockets of different sizes from a collection or set of available and differently sized sprockets. Each sprocket has a disc portion, with a series of teeth formed on an outer edge thereof, and a hub for coupling the sprocket to the driven shaft. The hub, which is integrally formed with the disc portion, will typically have a hex shaped bore, a square shaped bore, or a keyway that allows the hub to interface with the driven shaft so that the shaft will rotate with rotation of the sprocket. As noted above, to accommodate variations in seed types and field conditions, several sprockets are required and are typically stored on the agricultural implement itself. While reasonably effective, the collective size of the sprockets can be substantial, especially on an agricultural implement with limited space for storage of unused equipment.
Therefore, there is a need in the art to reduce the size of the sprockets to reduce storage loads on the agricultural implement without sacrificing the variability afforded by having multiple sprockets for accommodating variations in seed types and field conditions.